The present invention relates to a display device and a light guide plate thereof, and more particularly, to a display device with improved uniformity in luminance and a light guide plate thereof.
As a type of a light source device supplying light behind a screen of a liquid crystal display device, a backlight unit (BLU) is a core part that not only directly affects image quality such as luminance of image, color reproducibility, field of view, a ratio of light and shade, readability, etc., power consumption, product life, and the like, but also occupies about 20 to 50% of an overall unit price of a liquid crystal display device.
The backlight unit is mainly classified into a direct-lit type and an edge-lit type in accordance with a form of light source arrangement. The direct-lit type uses light projected toward a liquid crystal panel from a light source arranged right behind a screen, whereas in the edge-lit type, a light guide plate guides light projected toward a side direction from a light source arranged at an edge of a screen toward a liquid crystal panel to supply light to a display panel. Due to the structural difference, the direct-lit type is favorable to luminance, a ratio of light and shade, screen uniformity, image reproducibility, etc., whereas the edge-lit type is advantageous in terms of the thickness or cost of a product.
Recently, in the display industry, as a value of a display product as an interior design piece has become important, the percentage of an edge-lit backlight that has a great advantage in terms of an appearance of a product is gradually increasing. In particular, consumer demand for an extremely thin display product is increasing, and to keep pace with the trend, vigorous study has been carried out to minimize the number of diffusion sheets inserted behind a display panel since three to five diffusion sheets had been inserted behind the display panel. However, a display product with the minimum number of diffusion sheets cannot secure a light diffusion rate as before. Accordingly, uniformity in luminance of an output image is degraded, causing a hot spot to be noticeable.